Contract Assets And Liabilities (Schedule Of Contract Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Contract Assets and Liabilities [Abstract]
Retainage receivable	$ 530,897	$ 535,939	$ 535,939
Claims	577,811	549,849
Unapproved change orders	324,851	296,591
Other unbilled costs and profits	78,234	86,318
Total costs and estimated earnings in excess of billings	980,896	932,758	$ 932,758
Capitalized contract costs	35,746	32,773
Total contract assets	$ 1,547,539	$ 1,501,470